Frankia form symbiotic association with

Answer

**Step-by-Step Solution:**

1. **Understanding Frankia**: Frankia is a genus of bacteria that is known for its ability to fix nitrogen. It is a free-living organism, meaning it can exist independently in the soil.

2. **Symbiotic Association**: Frankia forms a symbiotic relationship with certain plants. In this relationship, both the bacteria and the plant benefit from each other. The plant provides the bacteria with shelter and nutrients, while the bacteria fix atmospheric nitrogen, which is essential for the plant's growth.

3. **Non-Leguminous Plants**: Unlike legumes, which have a well-known symbiotic relationship with Rhizobium bacteria, Frankia associates with non-leguminous plants. This is an important distinction because it highlights the diversity of symbiotic relationships in nature.

4. **Example of Symbiotic Plant**: One of the primary examples of a non-leguminous plant that forms a symbiotic association with Frankia is Alnus, commonly known as alder trees. These trees are able to thrive in nitrogen-poor soils due to the nitrogen-fixing capabilities of Frankia.

5. **Conclusion**: Therefore, the correct answer to the question "Frankia forms symbiotic association with" is **Alnus** or **non-leguminous plants**.

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